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/*
* linux/fs/f2fs/crypto_fname.c
*
* Copied from linux/fs/ext4/crypto.c
*
* Copyright (C) 2015, Google, Inc.
* Copyright (C) 2015, Motorola Mobility
*
* This contains functions for filename crypto management in f2fs
*
* Written by Uday Savagaonkar, 2014.
*
* Adjust f2fs dentry structure
* Jaegeuk Kim, 2015.
*
* This has not yet undergone a rigorous security audit.
*/
#include <crypto/hash.h>
#include <crypto/sha.h>
#include <keys/encrypted-type.h>
#include <keys/user-type.h>
#include <linux/crypto.h>
#include <linux/gfp.h>
#include <linux/kernel.h>
#include <linux/key.h>
#include <linux/list.h>
#include <linux/mempool.h>
#include <linux/random.h>
#include <linux/scatterlist.h>
#include <linux/spinlock_types.h>
#include <linux/f2fs_fs.h>
#include <linux/ratelimit.h>
#include "f2fs.h"
#include "f2fs_crypto.h"
#include "xattr.h"
/**
* f2fs_dir_crypt_complete() -
*/
static void f2fs_dir_crypt_complete(struct crypto_async_request *req, int res)
{
struct f2fs_completion_result *ecr = req->data;
if (res == -EINPROGRESS)
return;
ecr->res = res;
complete(&ecr->completion);
}
bool f2fs_valid_filenames_enc_mode(uint32_t mode)
{
return (mode == F2FS_ENCRYPTION_MODE_AES_256_CTS);
}
static unsigned max_name_len(struct inode *inode)
{
return S_ISLNK(inode->i_mode) ? inode->i_sb->s_blocksize :
F2FS_NAME_LEN;
}
/**
* f2fs_fname_encrypt() -
*
* This function encrypts the input filename, and returns the length of the
* ciphertext. Errors are returned as negative numbers. We trust the caller to
* allocate sufficient memory to oname string.
*/
static int f2fs_fname_encrypt(struct inode *inode,
const struct qstr *iname, struct f2fs_str *oname)
{
u32 ciphertext_len;
struct ablkcipher_request *req = NULL;
DECLARE_F2FS_COMPLETION_RESULT(ecr);
struct f2fs_crypt_info *ci = F2FS_I(inode)->i_crypt_info;
struct crypto_ablkcipher *tfm = ci->ci_ctfm;
int res = 0;
char iv[F2FS_CRYPTO_BLOCK_SIZE];
struct scatterlist src_sg, dst_sg;
int padding = 4 << (ci->ci_flags & F2FS_POLICY_FLAGS_PAD_MASK);
char *workbuf, buf[32], *alloc_buf = NULL;
unsigned lim = max_name_len(inode);
if (iname->len <= 0 || iname->len > lim)
return -EIO;
ciphertext_len = (iname->len < F2FS_CRYPTO_BLOCK_SIZE) ?
F2FS_CRYPTO_BLOCK_SIZE : iname->len;
ciphertext_len = f2fs_fname_crypto_round_up(ciphertext_len, padding);
ciphertext_len = (ciphertext_len > lim) ? lim : ciphertext_len;
if (ciphertext_len <= sizeof(buf)) {
workbuf = buf;
} else {
alloc_buf = kmalloc(ciphertext_len, GFP_NOFS);
if (!alloc_buf)
return -ENOMEM;
workbuf = alloc_buf;
}
/* Allocate request */
req = ablkcipher_request_alloc(tfm, GFP_NOFS);
if (!req) {
printk_ratelimited(KERN_ERR
"%s: crypto_request_alloc() failed\n", __func__);
kfree(alloc_buf);
return -ENOMEM;
}
ablkcipher_request_set_callback(req,
CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
f2fs_dir_crypt_complete, &ecr);
/* Copy the input */
memcpy(workbuf, iname->name, iname->len);
if (iname->len < ciphertext_len)
memset(workbuf + iname->len, 0, ciphertext_len - iname->len);
/* Initialize IV */
memset(iv, 0, F2FS_CRYPTO_BLOCK_SIZE);
/* Create encryption request */
sg_init_one(&src_sg, workbuf, ciphertext_len);
sg_init_one(&dst_sg, oname->name, ciphertext_len);
ablkcipher_request_set_crypt(req, &src_sg, &dst_sg, ciphertext_len, iv);
res = crypto_ablkcipher_encrypt(req);
if (res == -EINPROGRESS || res == -EBUSY) {
BUG_ON(req->base.data != &ecr);
wait_for_completion(&ecr.completion);
res = ecr.res;
}
kfree(alloc_buf);
ablkcipher_request_free(req);
if (res < 0) {
printk_ratelimited(KERN_ERR
"%s: Error (error code %d)\n", __func__, res);
}
oname->len = ciphertext_len;
return res;
}
/*
* f2fs_fname_decrypt()
* This function decrypts the input filename, and returns
* the length of the plaintext.
* Errors are returned as negative numbers.
* We trust the caller to allocate sufficient memory to oname string.
*/
static int f2fs_fname_decrypt(struct inode *inode,
const struct f2fs_str *iname, struct f2fs_str *oname)
{
struct ablkcipher_request *req = NULL;
DECLARE_F2FS_COMPLETION_RESULT(ecr);
struct scatterlist src_sg, dst_sg;
struct f2fs_crypt_info *ci = F2FS_I(inode)->i_crypt_info;
struct crypto_ablkcipher *tfm = ci->ci_ctfm;
int res = 0;
char iv[F2FS_CRYPTO_BLOCK_SIZE];
unsigned lim = max_name_len(inode);
if (iname->len <= 0 || iname->len > lim)
return -EIO;
/* Allocate request */
req = ablkcipher_request_alloc(tfm, GFP_NOFS);
if (!req) {
printk_ratelimited(KERN_ERR
"%s: crypto_request_alloc() failed\n", __func__);
return -ENOMEM;
}
ablkcipher_request_set_callback(req,
CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
f2fs_dir_crypt_complete, &ecr);
/* Initialize IV */
memset(iv, 0, F2FS_CRYPTO_BLOCK_SIZE);
/* Create decryption request */
sg_init_one(&src_sg, iname->name, iname->len);
sg_init_one(&dst_sg, oname->name, oname->len);
ablkcipher_request_set_crypt(req, &src_sg, &dst_sg, iname->len, iv);
res = crypto_ablkcipher_decrypt(req);
if (res == -EINPROGRESS || res == -EBUSY) {
BUG_ON(req->base.data != &ecr);
wait_for_completion(&ecr.completion);
res = ecr.res;
}
ablkcipher_request_free(req);
if (res < 0) {
printk_ratelimited(KERN_ERR
"%s: Error in f2fs_fname_decrypt (error code %d)\n",
__func__, res);
return res;
}
oname->len = strnlen(oname->name, iname->len);
return oname->len;
}
static const char *lookup_table =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+,";
/**
* f2fs_fname_encode_digest() -
*
* Encodes the input digest using characters from the set [a-zA-Z0-9_+].
* The encoded string is roughly 4/3 times the size of the input string.
*/
static int digest_encode(const char *src, int len, char *dst)
{
int i = 0, bits = 0, ac = 0;
char *cp = dst;
while (i < len) {
ac += (((unsigned char) src[i]) << bits);
bits += 8;
do {
*cp++ = lookup_table[ac & 0x3f];
ac >>= 6;
bits -= 6;
} while (bits >= 6);
i++;
}
if (bits)
*cp++ = lookup_table[ac & 0x3f];
return cp - dst;
}
static int digest_decode(const char *src, int len, char *dst)
{
int i = 0, bits = 0, ac = 0;
const char *p;
char *cp = dst;
while (i < len) {
p = strchr(lookup_table, src[i]);
if (p == NULL || src[i] == 0)
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